Fluid compression device



Sept. 21, 1937. H. c. BOWEN FLUID COMPRE-SSION DEICE Filed Jan. '25, 1935 om ww NQ IIII m wmp E www mamma sept. 21, 1937 FLUm coMPnEs'sIoNnnvlcE Herbert C. Bowen, Detroit, Mich., assignor to Hydraulic Brake Company, Detroit, Mich., a corporation oi.' California Application .muuuy z3, lesavseral No. 3,043

lClahn.

This invention relates to hydraulic brake systems and moreA particularly to a fluid kcompression device therefor. An object of' this invention is to provide a compression device having a conventional compression cylinder and interchangeable heads so that the cylinder may be readily converted into a comzpound compression cylinder.

Another object of the invention is to provide a 10 iiuld compression device including a cylinder having interchangeable heads. 4

Another object of the invention is to provide a compression device including a cylinderA and means for converting the cylinder into a compound cylinder.

A further-object of the invention is to provide a fluid compression device comprising va cylinder and a head therefor including a sleeve received by the cylinder to provide a cylinder having two chambers of different diameters.

Yet a further object of the invention is to provide a iiuid compression device comprising a cylinder readily convertible to a large compression chamber and a small compression chamber.

Other objects and features ofthe invention will appear from the following description taken in connection with'the drawing forming a part of this specication, `and in which,-

Fig. 1 is a schematic illustration of a complete hydraulic brake installation including an improved iluid compression; device;

Fig. 2 is a vertical sectional view of a fluid compression device embodying the invention;

Fig. 3 is a sectional view of a cylinder head;

g5 and Fig. 4 is a detail view. Referring to the drawing for more specific details of the invention, I8 represents a Vuid compression device including a reservoir I2 having 4o a filling opening I4 closed as by a plug I6 pro- 45 and the reservoir.

vided with suitable vents I8. Formed at the base of the reservoir is a cylinder 28.V This cylinder is open at both ends and has ports 22 and 24 providing communications between the cylinder inder 28 is closed as by a head 26 of a conventional vtype, such as is shown in Fig. 3.. Preferably the head is threaded in the cylinder.

It has been found desirable to change the cyl- 50 inder 28 into a compound cylinder, and to that end there is provided an interchangeable head `28. This head has a sleeve 38 which extends into the cylinder 28 to provide a plurality of chambers 82 and 34. The sleeve has a portion of small 1 i diameter which in conjunction with the wall of Generally one end ofthe cyl-` (Cl. Bil-54.6)

5 'Ihe head 28 has a discharge port 48 controlled as by a valve 42, and threaded in the discharge port isa coupling 44 connecting a fluid pressure switch 46, and the switch is connected in a circuit 48 including a battery 68 and a lamp 62, the circuit being suitably grounded as indicatedat 64 and 56.

Connected to the coupling 44 are uid pressuredelivery pipes or conduits 58 and 68 connected respectively to corresponding pairs of uid pressure motors 62, one pair for actuating the brakes associated with the frontl wheels of a vehicle and the other for actuating the brakes associated with the rear wheels of the vehicle. Each of the iluid pressure motors is connected between the separable ends of friction elements 64 and 66 for spreading these elements into drum engagement. As shown. each pair of friction elements is pivoted on a backing plate 68 associated with a rotatable drum 18 and the friction elements of each pair are connected to one another by a retractile spring 12.

When the cylinder 28 is converted into a compound cylinder by the use of the head 28, a compound compression piston is substituted for. a.- conventional piston. The compound compression piston employed is substantially the same as that covered in my co-pending application iiled September 16, 1933, Ser. No. 689.715,

As shown, a piston 14 reciprocable in the chambersv82 and 84 is held against displacement bya washer 16 supported on a retaining ring 18 tted in a circumferential groove in the wall of the cylinder adjacent the open end thereof. The piston has a head 88 and a skirt 82 reduced in diameter to provide in conjunction with the wall of the cylinder 28 an annular chamber 84 communicating with .the reservoir I2 as by way of the port 22.

A plug 86 threaded in the skirt of the piston provides, in conjunction with the skirt, a chamber 88 having a port 98 providing a communication Ybetween the chamber 88 and the chamber 84. The plug 86 has a groove for the reception of a leak-proof cup 92, and formed in the back of the plug is a recess 94 for the reception of one end of a thrust pin 96 the other end of which s suitably secured to a coupling 98 connected .as byY a boot |88 to the open end of the cylinder 28 so as to exclude dust and other foreign substances from the cylinder. The coupling 98 is connected to one end of a rod |02, the other end of which is connected to a foot pedal lever |04, and the lever is connected by a retractile spring |06 to a fixed support.

The head 80 of the piston has a plurality of ports or passages |08 providing communications between the annular chamber 84` and that portion of the chamber 32 forward of the head 80, and aleak-proof cup ||0 tted in a groove in the head with sufficient clearance to provide for longitudinal movement of the cup controls the.

ports |08. The head 80 has formed thereon a concentric sleeve ||2 having a plurality of ports ||4 providing communications between that portion of the chamber 32 forward of the head 80 and the interior of the sleeve. An annular Washer ||6 having notches ||8 in its periphery to provide for disinterrupted iiow of fluid is seated on the inner end of the sleeve 30, and a spring |20 is interposed between the washer and a shoulder on the head 80 for assisting in the return of the piston to retracted position.

The sleeve 2 carries a head |22 reciprocable in the chamber 34. This head has a plurality of ports |24 providing communications between the chamber 32 and the chamber 34, and a leak-proof cup |26 on the head for control of the ports |24 is held against displacement by a spring |28 interposed between the cup and the valve 42. This spring assists the spring |20 to return the piston to its normal or retracted position.

A piston |30 reciprocable in the sleeve ||2` extends through the piston head |22 on the sleeve ||2 and the leak-proof cup |26 on the piston head |22.` The cup prevents passage of fluid past the piston. As shown, a portion of the piston 30 is reduced in cross section to form an annular passage |32 providing a communication between the ports ||4 and the ohamber 88 in the skirt of the piston 80. The piston |30 carries a valve |34 urged by a spring |36 interposed between the plug 86 and the valveto seat the valve on a cushioned seat |38 to close the communication between the chamber 88 and that portion of the chamber 32 forward of the piston head 80.

In the operation of the device when the cylinder is converted into a compound cylinder, upon depressing the foot pedal lever |04 the lever is moved through an angle, and this movement is transmitted through the thrust pin |02 to move the piston 'I4 in the chambers 32 and 34. During the initial movement of the piston 14, the cup ||0 on the piston head 80 and the cup |26 on the piston head |22 close the ports 24 and 38, respectively, and pressure is received by the cup ||0 on the piston head 80. As the piston advances on its compression stroke, the fluid in the chamber 32 is displaced through the passages |24 in the piston head |22, past the cup |26 into the chamber 34, and thence through the valve 42 controlling the port 40. This valve prevents retrograde movement of the fluid. The fluid passes through the valve 42., the port 40 and the coupling 44, and thence through delivery pipes o; conduits 58 and 60 to the fluid pressure motors Movement of the fluid under pressure through the coupling 44 results in actuation of the switch 46 to close the circuit 48. This results in lighting the signal lamp 52. Simultaneously therewith, the fluid, moving under pressure through the delivery pipes or conduits 58 and 60, causes actuation of the fluid pressure motors 62 to spread the friction elements 64 and 66 against the resistance of retractile springs 12 into engagement with the drums 10.

When the fluid in the chambers 32 and 34 is placed under a pressure which when multiplied by the area of the head of the piston |30 and the area of the valve |34 is slightly in excess of the load on the compression spring |36, the piston |30 is moved to trip the valve |34 resulting in relief of the pressure onv the fluid in the chamber 32, and a portion of the fluid is returned from the chamber 32 through the passage ||4, the chamber B8, the port 90, the chamber 84, and the port 2-2 to the reservoir.

As the valve |34 opens the pressure on the fluid is transferred without loss from the piston head to the piston head |22 and tothe piston |30. Pressure on the piston |30, however, has been reduced by relief of the pressure on the valve |34,-hence the piston |30 returns to its retracted position and closes the valve |34.

Continued movement of the piston 'I4 results in building up pressure in both of the chambers 32 and 34 sufiiciently to again move the piston |30 and unseat the valve |34, and this operation is repeated until the pressure in the chamber 34 is of suiicient value to compress the spring |36l to retain the valve |34 in open position. This renders the head 80 ineffective.

Upon release of the applied force on the foot pedal lever |04, this lever is returned to its normal position by the retractile. spring |06. During this movement of the foot pedal lever the piston 14 is moved to its retracted position under' the influence of the return springs |20 and |28. Because of the limitation of space it has been found desirable to provide two return springs so that the load on the piston may be materially increased. This is not possible in instances Where only one return spring is employed.

As the piston returns to its retracted position, fluid is returned from the iiuid pressure motors 62 under pressure of the retractile springs 'I2 connected between the friction elements 64 and 66. Due to friction on the column of fluid in the chambers 32 and 34 and the delivery pipes or conduits 58 and 60 connecting the cylinder of the compression device to the fluid pressure motors, and. to the tension of the springs |20 and |28, the piston 14- returns to its retracted position slightly in advance of the return of the fluid to the cylinder of the compression device. This causes a partial vacuum in the chambers 32 and 34 resulting in collapseof the cups ||0 and 26 and admission of fiuid from the reservoir to the chambers 32 and 34.

Upon complete 4return of the piston 14 to its retracted position, the ports 24 and 38 are uncovered, whereupon further pressure in the chambers 32 and 34 due to the return of the uid from the fluid pressure motors 62 causes the cups to return to static condition, and any excess uid returned to the chambers 32 and 34 from the'uid pressure motors 62 passes from the chambers 32 and' 34 through the port 38, the passage 36, and the port 24 to the reservoir.

Although this invention has been described in connection with certain specific embodiments, the principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. 'Ihe invention is, therefore, to be limited only by the scope of the appended claim.

Having thus described the various features of high-pressure piston detachably secured to said tubular sleeve and located in the sleeve-like part of said cylinder head, said part having a port forward of the retractedposition of the highpressure piston, a plunger guided in said tubuf lar sleeve and having a relief valvel for the lowpressure cylinder, means for advancing said detachably connected pistons under applied lpressure, and a spring compressed between the lowpressure piston and cylinder head sleeve for re- 10 turning said pistons to retracted position.

mRBERT c. Bowles.l 

